.beta.-Adrenergic receptors were characterized in human neutrophil sonicates. In the present study the intact neutrophil was assessed for the number and affinity of .beta.-adrenergic binding sites by using the antagonist DHA [dihydroalprenolol]. Agonist and antagonist potencies, characterized by their effect on DHA binding and cAMP accumulation, are compared with agonist inhibition of lysosomal enzyme (.beta.-glucuronidase) release. Criteria for .beta.-adrenergic receptor identification were successfully demonstrated. At 30.degree. C, .beta.-adrenergic binding was rapid (t1/2 [half-time] 2 min) and reversible (t1/2 9 min). Receptor binding was saturable, revealing .apprx. 900 high-affinity receptors/neutrophil with DHA concentrations of 0.1-10 nM. By using both equilibrium and kinetic techniques, the Kd was determined to be .apprx. 0.6 nM. Agonists and antagonists completed for DHA binding in a manner consistent with their effect on cAMP generation. Rank order potency was suggestive of a .beta.-2 receptor: isoproterenol > epinephrine > norepinephrine. Stereoselectivity was shown by the greater potency of L-propranolol compared to the D isomer. A high degree of receptor-adenylate cyclase coupling efficiency was suggested by the observation that with only 1% receptor occupancy isoproterenol stimulated 50% maximal cAMP generation. There was an excellent correlation between the isoproterenol concentration which caused 50% of maximal inhibition of .beta.-glucuronidase release (K, inhibition constant) and that causing 50% maximal cAMP stimulation (Kact [activation constant]), suggestive of a close relationship between .beta.-adrenergic-induced adenylate cyclase activation and .beta.-adrenergic regulation of neutrophil lysosomal enzyme release. The data presented suggest that the use of the intact neutrophil for study of the .beta.-adrenergic receptor is feasible and may provide information which is considerably more closely related to modulation of physiological function by neurohormones than is possible with disrupted cell preparations.